基于有限元法的现浇箱梁偏心增大系数计算

根据公路桥梁相关规范,通过有限元计算软件二次开发,运用实体单元有限元法对6 000余座混凝土现浇箱梁的偏心增大系数进行计算。结果表明:车道数相同时,箱梁宽跨比越大,偏心增大系数越大,反之越小。初步确定简支箱梁的偏心增大系数在1.15～1.5之间。建立了可用于精确求解简支梁偏心增大系数的计算公式。计算连续梁偏心增大系数时,可根据简支梁公式求出各跨的偏心增大系数,并进行修正及取最大值。连续梁修正系数可根据经验在1.05～1.1之间确定,当箱梁较宽、总跨径较小、计算跨距离梁端较远时,宜选择较大的修正系数,反之选择较小值。提出了一种批量建立箱梁有限元实体单元模型、计算和分析数据的方法,可快速准确地研究其受力性能,实现高效便捷地精细化设计。

Study on eccentric-loaded coefficients of cast-in-place box girder by solid FEM

The eccentric-loaded coefficients of more than 6 000 concrete cast-in-place box girders were analyzed by the secondary development of FEM software based on solid FEM,according to the relevant code of road and bridge. The results showed that the coefficient of eccentricity increased with the increase of the width-span ratio if the number of lanes was the same. It was found that the appropriate coefficient of a simply supported box girder could be taken from 1.15 to 1.5 and a formula was thus obtained to calculate the coefficient accurately. For the continuous box girder, the coefficient of each span could be solved by the above-mentioned formula, and revised according to the revised factor, with the maximum value taken as the coefficient of the bridge. The revised factor for the continuous box girder could be taken from 1.05 to 1.1. A larger correction coefficient was appropriate to select once the width-span ratio value was large or the span was far from the end of the beam, while a smaller one should be chosen on the contrary. In conclusion, this paper presented a batch method for establishing the solid FEM box girder model as well as its calculation and analysis processes.The method would be helpful in the study of the mechanical properties of the box girder, thus achieving a detailed and efficient design of it.